This is a long-term, multi-center, observational study in children 2.5 to <17 years with achondroplasia (ACH). The objective is to evaluate growth, ACH-related medical complications, assessments of health-related quality of life, body pain, functional abilities, cognitive functions, and treatments of study participants. No study medication will be administered.

Key Inclusion Criteria:

• Signed informed consent by study participant or parent(s) or legally authorized representative (LAR) and signed informed assent by the study participant (when applicable)
• Aged 2.5 to <17 years at study entry
• Diagnosis of ACH
• Study participants and parent(s) or LAR(s) are willing and able to comply with study visits and study procedures

Key Exclusion Criteria:

• Have hypochondroplasia or short stature condition other than ACH (e.g. trisomy 21, pseudoachondroplasia, psychosocial short stature)
• In females, having had their menarche
• Height < -2 or > +2 standard deviations for age and sex based on reference tables on growth in children with ACH
• Annualized height growth velocity ≤1.5 cm/year over a period ≥6 months prior to screening
• Current evidence of corneal or retinal disorder/keratopathy
• Current evidence of endocrine alterations of calcium/phosphorus homeostasis
• Have a concurrent disease or condition that in the view of the Investigator and/or Sponsor, may impact growth or where the treatment is known to impact growth.
• Significant abnormality in screening laboratory results.
• Have been treated with growth hormone, insulin-like growth factor 1 (IGF 1), or anabolic steroids in the previous 6 months or long-term treatment (>3 months) at any time
• Have had regular long-term treatment (>1 month) with oral corticosteroids (low-dose ongoing inhaled steroid for asthma is acceptable)
• Have had previous guided growth surgery or limb-lengthening surgery within 12 months prior to screening.

Children with achondroplasia